It is costly to deliver containers, such as Front Opening Unified Pods (FOUPs) and Standard Mechanical Interface (SMIF) pods, to processing tools and load ports in a semiconductor fabrication facility. One method of delivering FOUPs or bottom opening containers between processing tools is an overhead transport (OHT) system. The OHT system lowers a FOUP onto the kinematic plate of the load port at approximately 900 mm height from the fabrication facility floor. An OHT system uses sophisticated ceiling mounted tracks and cable hoist vehicles to deliver FOUPs to, for example, a load port of a processing tool. The combination of horizontal moves, cable hoist extensions, and unidirectional operation, must be coordinated for transporting FOUPs quickly between processing tools. A transport vehicle must be available at the instant when a processing tool needs to be loaded or unloaded for best efficiency.
OHT systems are often mounted on portions of a facility ceiling, and therefore, are located above the processing tools and load ports. OHT systems utilize free space in the fabrication facility as the processing tools are typically floor mounted equipment. Ceiling mounted OHT systems must raise or lower a container a substantial distance between the OHT track and, by way of example only, a load port. An OHT system preferably has a very high cleanliness performance because any particles created from moving FOUPs along the track may fall onto the tool areas located underneath and potentially damage wafers.
Rail guided vehicles (RGVs) and automatic guided vehicles (AGVs) are often utilized in semiconductor fabrication facilities to move containers along the facility floor between processing tools. RGV's and AGV's are easier to access for maintenance purposes than an OHT system and are typically less costly than ceiling mounted OHT systems. Particle control is also simplified because particles generated by an RGV or AGV remain below the datum plane of a load port. RGVs and AGVs, however, occupy valuable floor space—which is at a premium in a semiconductor fabrication facility—and pose safety issues (e.g., tool operators and RGV's operate in the same space).
An example of an interface between an Automated Material Handling System (AMHS) conveyor in a semiconductor fabrication facility and a process tool is described and claimed in U.S. patent application Ser. No. 11/064,880, entitled “Direct Tool Loading,” which is assigned to Asyst Technologies, Inc, and is incorporated by reference herein. For example, one embodiment of the Direct Tool Loading invention includes a conveyor that delivers semiconductor material containers to a process tool. The conveyor is preferably located below the kinematic plate of the load port. In a preferred embodiment, the kinematic plate moves substantially vertically to move a container between the conveyor and a position where the process tool can access the materials located in the container.
Not every processing tool will be able to, or will require, use of a Direct Load load port. In fact, there likely will be a need to interface a floor mounted conveyor to a conventional load port such as, by way of example only, the load port disclosed in U.S. Pat. No. 6,419,438, entitled “FIMS Interface Without Alignment Pins,” which is assigned to Asyst Technologies, Inc., and is incorporated by reference herein. A standard load port can conform to the SEMI BOLTS interface standard but is not limited by all of the BOLTS requirements such as the single piece, front mounting plate. The standard loadport referred to in this description could have separate modules for the port door, door lift, or kinematic plate assembly. The important requirement is that the loadport's kinematic plate can receive the container in the manner described by the SEMI standard.
This is a description of an invention that facilitates the loading of containers from the above-described conveyor to a standard loadport on a process tool. The conveyor could also be mounted slightly above the floor or below the floor in this invention.